You should check with your credit card company as it varies with "primary" and "secondary" coverage. There are insurance policies that you (I say "you", but I am in the UK and assume similar exists in the US) may be able to take out a separate car hire excess insurance policy. I am not associated with them in any way apart from as a customer but this is who I use and it was cheaper than buying the rental companies excess protection - in fact it cost less for the policy for a year than it would have for 5 days rental. This is the company: https://www.carhireexcess.com/ and it covers me worldwide with CDW also included in the US.